/*
 * Copyright (c) 2010, okazoh_tk. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  - Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *  - Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *  - Neither the name of the copyright holder nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef ALKES_MEMORY_TEXTEND_POLICY_H_INCLUDED_
#define ALKES_MEMORY_TEXTEND_POLICY_H_INCLUDED_

#include "alkes/internal.h"
#include "alkes/core/Memory.h"
#include <string.h>

namespace alkes {

struct StdlibAllocator
{
    static void* allocate(uint32_t size)
    {
        return alkes_malloc(size);
    }

    static void deallocate(void* ptr)
    {
        alkes_free(ptr);
    }
};

template<class Allocator>
struct NoCopyExtendPolicy
{
    typedef Allocator allocator_type;

    static void* extend(void* old_buffer, uint32_t& old_size, uint32_t new_size);
};

template<class Allocator>
void* NoCopyExtendPolicy<Allocator>::extend(void* old_buffer, uint32_t& old_size, uint32_t new_size)
{
    // enough buffer
    if (new_size <= old_size)
        return old_buffer;

    if (old_buffer)
    {
        Allocator::deallocate(old_buffer);
    }

    old_buffer = Allocator::allocate(new_size);

    if (old_buffer)
        old_size = new_size;    // new buffer size
    else
    {
        AL_ASSERT(false);
        old_size = 0;
    }

    return old_buffer;
}

template<class Allocator>
struct CopyExtendPolicy
{
    typedef Allocator allocator_type;

    static void* extend(void* old_buffer, uint32_t& old_size, uint32_t new_size);
};

template<class Allocator>
void* CopyExtendPolicy<Allocator>::extend(void* old_buffer, uint32_t& old_size, uint32_t new_size)
{
    // enough buffer
    if (new_size <= old_size)
        return old_buffer;

    void* new_buffer = Allocator::allocate(new_size);
    if (!new_buffer)
        return 0;

    if (old_buffer)
    {
        memcpy(new_buffer, old_buffer, old_size);
        Allocator::deallocate(old_buffer);
    }

    old_buffer = new_buffer;
    old_size = new_size;    // new buffer size

    return old_buffer;
}

}

#endif
